EVEN a man as tone-deaf as James Dolan has to understand he has reached a critical stage now, a point of no return. The relationship between his basketball coach and his basketball fans is broken, irretrievably and irreversibly. This is not a stage. This is not a phase. This is real. This is permanent.

Knicks fans have chanted for scalps before, and they’ve always gotten them eventually: Scott Layden, Don Chaney, even Hubie Brown back in the day. But this is different, much different. This is anger on HGH. This is fury multiplied by millions.

The Knicks insisted the man who was ejected from Monday night’s calamitous 119-92 Garden loss to the Pacers wasn’t tossed because of the “Fire Isiah” signs he lugged into the building, but because of his accompanying behavior, alternately described yesterday as “obnoxious,” “profane” and “bothersome to other customers.”

That’s fair. You don’t have to crane your neck most nights at the Garden to see similarly-crafted pieces of oak tag, construction paper or bed sheets containing similar pleas for basketball justice. The First Amendment isn’t being trampled at Penn Plaza, just the patience and the basketball sensibility of its constituency.

And that’s the issue. You can make signs disappear. You can’t make the venom disappear. That stays. That’s on Dolan, who stubbornly refuses to concede what’s long become apparent, that Isiah Thomas’ time is over, and has been over for over a year. And it’s on Isiah, who after Monday’s disgrace all but laid out a paper trail of quotes why he should be fired as soon as possible, and continued to do so yesterday.

“You know, as an athlete, your job is to bring pride and heart to the game,” Thomas said after practice at the Knicks’ practice facility in Westchester County. “Our job as coaches is to bring some strategy to the game, but the heart and the toughness as a competitor, that’s what the athlete needs to bring.”

Actually, Thomas’ job as the team’s president and chief architect was to identify and acquire players who might actually enjoy breaking the occasional sweat during basketball games. Had he done that, then Thomas’ job as a coach might have been a little easier than having to plead them into acting the part. Although, given the woeful job Thomas the Coach has done this year, it might not have mattered anyway.

For Isiah to blast his team’s heart now is to listen to a man begging for a buyout. These players are all his, and they can mostly be divided into three categories:

1. Those who have regressed on his watch – Eddy Curry, Quentin Richardson, David Lee and Nate Richardson.

3. The coolers – Stephon Marbury, whose old team, the Suns, immediately rose to NBA Elite status once he left; and Zach Randolph, whose old team, the Trail Blazers, is presently riding an eight-game winning streak.

Really, it’s impossible to know if Thomas has been a bigger failure as a coach or a GM, and that is some kind of historic exacta.

Which leads us back to the nightly passion plays at the Garden, where the chanting has become louder and the misery tangible, where this morning at 11 a.m. there will be another public protest where an eight-foot pink slip will be unveiled by a longtime Knicks fan named Dr. Art Nathan with the idea of gathering signatures of fellow disgruntled and disillusioned fans. He shouldn’t have a terribly difficult time filling it up.

Meanwhile, Isiah is busy filling tape recorders with bizarre observations when he should be filling up cardboard boxes with his belongings. This, too, is from yesterday:

“Probably the most humiliating experience I’ve had in my life is standing in a soup line and kids from school walking by laughing at you. This is kind of the equivalent of that type of humiliation.”

Read that paragraph again, if you can stomach it.

This has to change. It has to. The men who run Madison Square Garden can frown and grit their teeth and rage about the negative vibes that fill their building night after night after night, they can confiscate signs and try to eradicate the bile boiling in their corridors. And really, they should be happy to have it. Because once the people are done with their anger, they replace it with apathy.